python-pytest in references graph

[Roel Janssen]

Dear Guix,

I'm trying to understand the output of:
$ guix graph --type=references python-rdflib | dot -Tsvg -o rdflib.svg

Particularly, I'm looking at why python-pytest has an input arrow from 
python-rdflib, while it's
"only" a native-input?  I thought the "references" graph type would only 
include run-time
references, but I don't know what happens in this case.

What am I missing?

Thank you for your time.

Kind regards,
Roel Janssen